A utility truck crashed into a school bus at a highway intersection Thursday, injuring 11 students, one of whom was airlifted to a Des Moines hospital in serious condition.

Five other students were hospitalized in stable condition, and the others were treated and released, authorities said.

The crash happened about 7:55 a.m. at an intersection with U.S. Highway 71 in Audubon, the Iowa State Patrol said. Audubon Community Schools Superintendent Ron Dobson said there were 20 students on the bus at the time ranging from kindergarten through eighth grade.

Dobson didn't know the extent of damage to the bus, which was hit on its right side between the wheel wells. The truck driver was taken to a hospital and his condition was unknown.

Audubon, 70 miles west of Des Moines, has about 2,200 residents.